The signal transduction cascades ras-Raf-Mek-Erk and PI3K-Akt play a central role in cell growth, cell proliferation, apoptosis, adhesion, migration and glucose metabolism. Consequently, the fundamental involvement in the pathogenesis of diseases such as cancer, neurodegeneration and inflammatory diseases is proven both for the ras-Raf-Mek-Erk and for the PI3K-Akt signal pathway. The individual components of these signal cascades are therefore important therapeutic points of attack for intervention in various disease processes (Weinstein-Oppenheimer C. R. et al. 2000, Chang F. et al. 2003, Katso R. et al 2001 and Lu Y. et al 2003).
The molecular and biochemical properties of both signal pathways are first described separately hereinafter.
A plurality of growth factors, cytokines and oncogenes transduce their growth-promoting signals via the activation of G-protein coupled ras which leads to the activation of serine threonine kinase Raf and to the activation of mitogen-activated protein kinase kinase 1 and 2 (MAPKK1/2 or Mek1/2) and results in the phosphorylation and activation of MAPK 1 and 2—also known as extracellular signal regulated kinase (Erk1 and 2). Compared to other signal pathways, the ras-Raf-Mek-Erk signal pathway combines a large number of proto-oncogenes, including ligands, tyrosine kinase receptors, G-proteins, kinases and nuclear transcription factors. Tyrosine kinases such as, for example, EGFR (Mendelsohn J. et al., 2000) frequently mediate constitutively active signals to the downstream ras-Raf-Mek-Erk signal pathway in tumour events caused by overexpression and mutation. Ras mutations are mutated in 30% of all human tumours (Khleif S. N. et al., 1999, Marshall C., 1999), the highest incidence of 90% being found in pancreatic carcinomas (Friess H. et al., 1996, Sirivatanauksorn V. et al., 1998). For c-Raf a deregulated expression and/or activation has been described in various tumours (Hoshino R. et al., 1999, McPhillips F. et al., 2001). B-Raf point mutants were detected in 66% of all human malignant melanomas, 14% of all ovarian carcinomas and 12% of all carcinomas of the colon (Davies H. et al., 2002). It is therefore not surprising that Erk1/2 is primarily involved in many cellular processes such as cell growth, cell proliferation and cell differentiation (Lewis T. S. et al., 1998, Chang F. et al., 2003).
In addition, the members of the Raf kinases also have Mek-Erk-independent anti-apoptotic functions whose molecular steps have not yet been fully described. Ask1, Bcl-2, Akt and Bag1 have been described as possible interaction partners for the Mek-Erk-independent Raf activity (Chen J et al., 2001, Troppmaier J. et al., 2003, Rapp U. R. et al., 2004, Gotz R. et al., 2005). It is assumed nowadays that both Mek-Erk-dependent and Mek-Erk-independent signal transduction mechanisms control the activation of the upstream ras and Raf stimuli.
The isoenzymes of the phosphatidylinositol 3-kinases (PI3Ks) function predominantly as lipid kinases and catalyse the D3 phosphorylation of the second-messenger lipids Ptdlns (phosphatidylinositol) to Ptdlns(3)P, Ptdlns(3,4)P2, Ptdlns(3,4,5)P3 phosphatidylinositol phosphates. The class I PI3Ks are composed structurally of the catalytic (p110alpha, beta, gamma, delta) and the regulatory (p85alpha, beta or p101gamma) subunits. Furthermore, the class II (PI3K-C2alpha, PI3K-C2beta) and class III (Vps34p) enzymes belong to the family of the P13 kinases (Wymann M. P. et al., 1998, VanHaesebroeck B. et al., 2001). The PIP increase triggered by the PI3Ks activates the proliferative ras-Raf-Mek-Erk signal pathway via the coupling of ras on the one hand (Rodriguez-Viciana P. et al., 1994) and on the other hand stimulates the anti-apoptotic signal pathway by recruiting Akt to the cell membrane and consequent overactivation of this kinase (Alessi D. R. et al., 1996, Chang H. W. et al., 1997, Moore S. M. et al., 1998). Consequently, the activation of PI3Ks fulfils at least two crucial mechanisms for tumour formation, namely the activation of cell growth and cell differentiation and the inhibition of apoptosis. In addition, PI3K also have protein-phosphorylating properties (Dhand et al., 1994, Bondeva T. et al., 1998, Bondev A. et al., 1999, VanHaesebroeck B. et al., 1999) which can trigger a PI3Ks-intrinsically regulating serine autophosphorylation for example. In addition, it is known that PI3Ks also have kinase-independent regulating effector properties, e.g. during control of cardiac contraction (Crackower M. A. et al., 2002, Patrucco et al., 2004). It is furthermore proven that PI3Kdelta and PI3Kgamma are specifically expressed on hematopoietic cells and therefore constitute potential points of attack for isoenzyme-specific PI3Kdelta and PI3Kgamma inhibitors in the treatment of inflammatory diseases such as rheumatism, asthma and allergies and in the treatment of B and T cell lymphomas (Okkenhaug K. et al., 2003, Ali K. et al., 2004, Sujobert P. et al., 2005). PI3Kalpha, which was recently identified as a proto-oncogene (Shayesteh L. et al., 1999, Ma Y. Y. et al., 2000, Samuels Y. et al., 2004, Campbell I. G. et al., 2004, Levine D. A., 2005) is considered to be an important target in the treatment of tumour diseases. The importance of PI3K species as a target for the development of active substances is therefore extremely diverse (Chang F. & Lee J. T. et al, 2003).
The kinases related to PI3K (PIKK), which include the serine/threonine kinases mTOR, ATM, ATR, h-SMG-1 and DNA-PK (Chiang G. G. et al 2004) are also of great interest. Their catalytic domains have a high sequence homology to the catalytic domains of PI3Ks.
In addition, the loss of the tumour suppressor protein PTEN (Li J. et al., 1997, Steck P. A. et al., 1997)—whose function is the reversion of the phosphorylation initiated by the PI3K—contributes to an overactivation of Akt and its downstream cascade components and thereby emphasise the causal importance of PI3K as a target molecule for tumour therapy.
Various inhibitors of individual components of the ras-Raf-Mek-Erk and PI3K-Akt signal pathways have already been published and patented.
The present state of development in the field of kinase inhibitors, in particular of the ras-Raf-Mek-Erk and PI3K-Akt pathway, is described in the reviews of H. T. Arkenau et al, 2011, M. S. Chapman & J. N. Miner, 2011 and P. Liu et al, 2009. These publications contain comprehensive listings of the published low-molecular ras-Raf-Mek-Erk- and PI3K inhibitors.
The kinase inhibitor Sorafenib (Bay 43-9006; WO 99/32111, WO 03/068223) which was approved in, 2006 shows a relatively non-specific inhibition pattern of serine/threonine and of tyrosine kinases such as Raf, VEGFR2/3, Flt-3, PDGFR, c-Kit and other kinases. Great importance is attached to this inhibitor in angiogenesis-induced advanced tumour diseases (e.g. in renal cell carcinoma) and also in melanomas having a high B-Raf mutation rate. No inhibition of the kinases in the PI3K-Akt signal pathway has been described for Bay 43-9006. Other Raf-specific inhibitors like PLX-4032 and GSK2118436 (Arkenau H. T. et al, 2011) are currently under clinical evaluation.
Several Mek1/2 inhibitors (AZD-6244, XL-518, GSK1120212 and others) currently undergo clinical testing (reviewed by M S Chapman & J N Miner, 2011). However, no interaction with Erk1 or Erk2 nor any PI3K-Akt signal pathway inhibiting function or its simultaneous modulation has yet been disclosed for these Mek inhibitors.
Patent specification WO 2009/077766 describes pyrido[2,3-b]pyrazines as RAF inhibitors.
In addition, the patent specifications WO 2008/040820, WO 2008/009908 and WO 2005/123733 describe pyrido[2,3-b]pyrazines as agrochemical fungicides and herbicides, respectively.
The Korean invention KR 2008004646 relates to 2-alkenyloxy-3-ethynylpyrido[2,3-b]pyrazine derivatives and their pharmaceutically salts which with inhibit the expression of hypoxia-inducible transcriptional factor 1 (HIF-1) gene.
Patent specifications WO 04/104002 and WO 04/104003 describe pyrido[2,3-b]pyrazines, which can be substituted in the 6- or 7-position with urea, thiourea, amidine or guanidine groups. These compounds possess properties as inhibitors or modulators of kinases, in particular of tyrosine and serine/threonine kinases, and a use as a medicament is specified. However, no use of these compounds as modulators of lipid kinases, alone or in combination with tyrosine and serine/threonine kinases has been described.
In addition, patent specification WO 99/17759 describes pyrido[2,3-b]pyrazines which, among other things, carry alkyl-, aryl- and heteroaryl-substituted carbamates in the 6-position. These compounds are to be used to modulate serine threonine protein kinases.
Patent specification WO 05/007099 describes, among other things, urea-substituted pyrido[2,3-b]pyrazines as inhibitors of the serine/threonine kinase PKB. A use in the treatment of cancer diseases is specified for these compounds. However, no specific examples of urea-substituted pyridopyrazines with these biological properties are given.
Further examples of pyrido[2,3-b]pyrazines substituted with urea in the 6- and 7-position are given in patent specification WO 05/056547. The compounds in this patent specification are described as inhibitors of protein kinases, in particular GSK-3, Syk und JAK-3. A use in the treatment of proliferative diseases is given for these compounds among other things. No use of these compounds as modulators of lipid kinases, alone or in combination with serine/threonine kinases is described.
The patent application WO 04/005472 describes, among other things pyrido[2,3-b]pyrazines substituted with carbamate in the 6-position which inhibit the growth of bacteria as antibacterial substances. No antitumour effect is described.
Certain diphenyl quinoxalines and pyrido[2,3-b]pyrazines with special alkylpyrrolidine, alkylpiperidine or alkyl sulfonamides group at a phenyl ring which can additionally also bear urea or carbamate substitutions in the 6- or 7-position are described in patent specifications WO 03/084473, WO 03/086394 and WO 03/086403 as inhibitors of the activity of the serine/threonine kinase Akt. A use in the treatment of cancer diseases is specified for these compounds. No defined indication of a biological effect is given for the pyrido[2,3-b]pyrazine compounds described therein as examples.
Patent specification WO 03/024448 describes amide and acrylamide-substituted pyrido[2,3-b]pyrazines which can also contain carbamates as additional substituents and can be used as histone deacetylase inhibitors for the treatment of cell proliferation diseases.
The publication (S. Laufer, J. Med. Chem. 2010, 53(3), 1128-1137) describes pyridinylpyridopyrazines as lead compounds for novel p38α Mitogen-Activated Protein Kinase Inhibitors.
In another publication (M. R. Dobler, Pest Management Science, 2010, 66(2), 178-185) pyrido[2,3-b]pyrazines are described as tubulin polymerisation promoters.
In the publication (Temple C. et al. 1990) the synthesis of a 6-ethylcarbamate-substituted pyrido[2,3-b]pyrazine derivative is described as one example. No antitumour effect is disclosed or made obvious.
The synthesis of further derivatives of 6-ethylcarbamate-substituted pyrido[2,3-b]pyrazine is described in a publication by R. D. Elliott (J. Org. Chem. 1968). No biological effect of these compounds is described or disclosed.
The publication by C. Temple (1968) describes the synthesis and investigation of 6-ethylcarbamate-substituted pyrido[2,3-b]pyrazines as potential antimalarial drugs. No antitumour effect is disclosed or made obvious.
Several PI3K inhibitors (NVP-Bez-235, GDC-0941, XL-147 and others) undergo clinical trials (reviewed by Maira S. M., et al, 2010).